I understand on real life railroads if there is a bridge that only has a single length of track, usually there is a siding at either end to allow one track to wait and one pass over the bridge.I had the idea, to model a bridge with double track that would serve as siding, but suspended by a bridge. I think it would be a neat scene, but I dont know if on a real world railroad it would be posisble. The windage could topple high loads, and even spread coal dust should a coal train be waiting.
What do you think?
Yes there are bridges that have both a main and a siding.
The problem in model railroads is that the sidings are so incredibly short that it can look like the bridge is just under the area with the siding. On real railroad, a 4000-8000 foot siding can easily have a 500 ft foot bridge under the main and siding. In some parts of the country its pretty much impossible to go a mile without some sort of bridge or culvert.
If there is a reason that they move a siding where it isn't on a bridge, its because a double track bridge costs more than a single track bridge to the reason would be cost, not necessarily wind.
Dave H. Painted side goes up. My website : wnbranch.com
As I understand it, there was a long trestle across the Great Salt Lake in Utah with a full station in the middle called Mid Lake owned by Southern Pacific? I presume it would have been for crossing of trains purposes only. Can't imagine there would have been local switching!
Here in Melbourne Australia, there is a station called Victoria Park where electric suburban trains are stabled on a bridge which carries the railway over a 10 lane freeway.
https://www.google.com.au/maps/place/Victoria+Park+Station/@-37.7956476,144.9946395,72m/data=!3m1!1e3!4m5!3m4!1s0x6ad6431cabb81893:0x8d6f687278038ff4!8m2!3d-37.7998707!4d144.9939779
The view presented from the Freeway is here
https://www.google.com.au/maps/@-37.7959253,144.9959438,3a,75y,290.17h,90t/data=!3m7!1e1!3m5!1s00aqfwkzqhTRsB1ZTRjRsw!2e0!6s%2F%2Fgeo0.ggpht.com%2Fcbk%3Fpanoid%3D00aqfwkzqhTRsB1ZTRjRsw%26output%3Dthumbnail%26cb_client%3Dmaps_sv.tactile.gps%26thumb%3D2%26w%3D203%26h%3D100%26yaw%3D342.99332%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192
So yes there are examples!
Cheers from Australia
Trevor
Often, there were formerly double-track segments that were reduced to single track with passing sidings either after installation of CTC or reduced traffic justified removal of most of the second track. Or, sometimes, there were double track bridges built in anticipation of increased traffic that never materialized.
Wheeling Bridge by Edmund, on Flickr
This Wheeling & Lake Erie bridge has been reduced to a single track line.
In some instances the second track was removed in order to center a track in a tunnel in order to improve clearances for excess-height cars such as this example:
Wheeling_Ohio by Edmund, on Flickr
I modeled a spot on my layout showing a recently removed second track while retaining a portion used as a passing siding:
Track_joint1 by Edmund, on Flickr
IMG_8287_fix by Edmund, on Flickr
Good Luck, Ed
In practice, it would be rare to waste the considerable additional money to build a bridge to double-track width, and Cooper rating sufficient for two heavy trains on the structure together, just to have a siding where the stopped crew would be inconvenienced to get off. It's much cheaper, safer, and more convenient to have the sidings safely at the ends... or to have full double track across the bridge.
The argument is similar to having switches or wyes out on elevated structure; I can think offhand of two that do this (on B&O and WP) but these both have little good alternative to placement there.
In addition, the sometimes-tried expedient of reducing bridge loading without using turnouts at either end, through the expedient of gantleted track, can't be used with passing sidings, although it happily allows half the number of actual switches to serve a restricted-width bridge than full sidings would.
It does occur to me that there might be prototype situations where putting a passing siding on a bridge could make sense -- where the line is cut into an unstable mountainside or ravine wall for some distance and it would be more expensive to make or maintain the added width of the siding 'at grade'. This might also apply to accommodating increased bidirectional traffic (with more inline meets) in a period where the cost of widening a bridge might be less than doing heavy grading adjacent to traffic...
Engi1487I think it would be a neat scene, but I dont know if on a real world railroad it would be posisble.
I don't understand why you would limit yourself to only things that can be verified to exist in the real world.
It is YOUR railroad, and if you want a passing siding on a bridge... do it!
Edit: OOPS! Nevermind. I did not see this was the "Prototype Information" section, I though it was the "Layout Building" section.
Sorry, and ignore my comment.
-Kevin
Living the dream.
xdfordlong trestle across the Great Salt Lake in Utah with a full station in the middle called Mid Lake owned by Southern Pacific
Midlake Station Lucin Cutoff
https://www.trestlewood.com/page/1023
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.
Well the PRR around North philadelphia station has numerous bridges. Eight deck girder bridges over Broad street and six over the Reading rr at the west end where the platform did go that far plus two for the Chestnut Hill branch. Since the corridor is elevated on fill there are many sidings that have parallel bridges to the mains over streets throughout Philadelphia.
I remember a picture on MR years ago of a switch on the PRR in the middle of a bridge. Was double track made partial single track. If I rememberr correctly it was in Philadelphua, PA.
Engi1487, in the interest of realism, the best approach I have found is to view the situation as the prototype would. The world of railroading seems to have no absolutes and, an example can be found to justify almost any thing. Railroads are in business to provide a service (transportation) as cheaply as possible, in order to maximize profits. Spending as little as possible is very crucial in achieving as low an operating ratio ( how much is spent to earn each dollar of revenue), as possible.
Plant rationlization to reduce operating expense means that EVERY thing must be justified by its necessity to produce revenue. With this in mind, every bridge, tunnel, track, building, etc., must be justified by its drain on the bottom line. That is why there are so many examples of former multi track pridges that now sport one track, roadbeds that no longer have any rails at all, where rails that at one time crossed routes on a diamond, they now cross using two regular turnouts instead. Bridgework, no matter how small or simple is an expense that is avoided if at all possible. If any alternative to locating a passing siding on a bridge (or in a tunnel) existed, that is the path most railroads would follow.
Model railroaders are generally looking for the complex and unusual in the search for making their railroads "interesting". Too many prototypically unjustifiable "interesting" features make the railroads cartoonish. Some examples that stand out to this observer are unjustifiable double or "scissors" crossovers, slip switches, and multiple track tunnels and bridges. Sure, they exist in the real world, but only when and where they can't be avoided and, traffic justifies them. As another responder to your question answered, it is your railroad, if you want it, you're paying the cost to be the boss, enjoy what YOU like!
There is an example on what is now Progressive Rail's "High Line" in Minnesota (originally Minneapolis Northfield & Southern). There's a two-track bridge over interstate 494; the line is single track until just before the bridge on the south (Bloomington) side, where it splits into two tracks until just beyond the north (Richfield) side where it goes back to single track. In this case, the passing siding was built on level ground long before the interstate came along (maybe 40-50 years before). Since the interstate is built below grade to avoid level crossing with streets, a railroad bridge had to be built so the interstate could go under it.
Although there are real-world examples (like the one I cited), I would agree with NHTX that a real railroad would do all it could to avoid a situation of having to build a double-track bridge to allow for a passing siding. I suspect the instances of a railroad having a double-track mainline that went down to a single-track to go across a bridge or through a tunnel is much more common than a railroad building a double-track bridge or tunnel to allow for a passing track. I think our model railroads are more realistic when they follow the most common thing a railroad would do, not pick out 'one off' exceptions to model.